I think the best way to do this would be to create a new table to collect ratings. The table should have a linked field to the table containing the list of songs as well as a rating field. You can then send people a form or give them access to this table where they can create a record with a rating and link it to a song.
In the songs table you can use roll up fields to calculate averages and totals of ratings.
You can also group your ratings table by the song they are linked to and you will see the spread of ratings on each song and you can change the aggregation settings in the group headers to see averages/totals/whatever stats you need.